Notes from Quantum Reality, 1985
by Nick Herbert
Reality is the real business of physics.
There is no quantum world. There is only an abstract quantum description.
The final truth about a phenomenon resides in the mathematical description of it; so long as there is no imperfection in this, our knowledge of the phenomenon is complete.
Sir James Jeans
One thing we are sure of, and that is the reality and substantiality of the luminiferous ether.
Far from being a crank or minority position, “There is no deep reality” represents the prevailing doctrine of establishment physics.
We now know that the moon is demonstrably not there when nobody looks.
N. David Mermin
The Copenhagen interpretation properly consists of
two distinct parts:
1. There is no reality in the absence of observation;
2. Observation creates reality.
George Boole, an Irish schoolteacher, reduced logical statements to simple arithmetic by inventing an artificial symbolic language which laid bare the logical bones of ordinary language.
Atoms are not things.
Werner von Heisenberg
Bohr believed that quantum theory is complete as it stands. It has no need of ordinary objects.
In John von Neumann’s famous book The Mathematical Foundations of Quantum Mechanics he offers a proof that states that if quantum theory is correct, the world cannot be made of ordinary objects.
Physical objects would have no attributes, von Neumann said, if a conscious observer were not watching them.
Von Neumann himself merely hinted at consciousness-created reality in dark parables. His followers boldly took his arguments to their logical conclusion.
In the experiments about atomic events we have to do with things and facts, with phenomena that are just as real as any phenomena in daily life. But the atoms and the elementary particles themselves are not as real; they form a world of potentialities or possibilities rather than one of things or facts.
Werner von Heisenberg
During the magic measurement act, one quantum possibility is singled out, abandons its shadowy sisters, and surfaces in our ordinary world as an actual event.
Classical physics built its world out of two kinds of entity: matter and field (also known as particle and wave). Quantum physics destroyed the once sharp distinction between matter and field.
It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature.
In 1952, despite von Neumann’s proof, David Bohm constructed a model of the electron with innate attributes whose behaviour matches the predictions of quantum theory.
If quantum theory ever collapses Bell’s theorem will survive its demise and impose non-locality on quantum theory’s successor. Because Bell’s theorem makes contact with a general feature of reality itself, it foretells the shape of all future physical theories.
The first quantum particle to be discovered—in 1897 by Joseph J. Thomson—was the electron.
Two waves can cross paths, form a momentary superposition, then continue on their ways entirely unchanged by their encounter—an option not generally available to other forms of being.
Whenever it is measured the world seems solid (particle-like), but the pattern formed by these particles leads to the conclusion that between measurements the world acts like a wave. Following this lead, quantum theory represents the unmeasured world as a wave identical in its behaviour to ordinary waves, but interpreted in a decidedly non-ordinary manner.
Because the quantum wave carries no energy, it is not directly detectable; we never see any quantum waves, only quantum particles.
The most important static attributes are mass, charge, and spin magnitude. The major dynamic attributes are position, momentum, and spin orientation.
The polarization attribute is an attribute closely related to the photon’s spin.
Quantum theory doesn’t describe things themselves. Rather it predicts the probability of their occurrence.
Feynman assumes that the unmeasured world works
according to two rules:
1. A single quantum particle takes all possible paths.
2. No path is better than any other.
The central postulate of orthodox ontology is this: All quantum particles represented by the same proxy wave are physically identical; identical situations give different results. That’s all there is to it.
A small but prestigious minority of physicists reject the orthodox ontology. They include Albert Einstein, Louis de Broglie, Erwin Schrodinger, David Bohm, and John Stewart Bell.
Considered as a particle, the hydrogen atom is mostly empty space. However, considered as a wave (realm of possibilities), the electron fills its atom brim to brim.
Human experience is invariably classical, but atoms don’t behave in a classical manner.
How the world appears to us must certainly depend on how we measure it, but it’s absurd to believe that how the world actually is is determined by human observational capacities.
A curious feature of the Copenhagen interpretation is that it considers both the quantum world and the measuring device to be incomprehensible.
Von Neumann’s world is entirely quantum—there’s not a bit of classical physics in it.
Since von Neumann could not find a natural place to locate the collapse of the wave function, he reluctantly came to the conclusion that human consciousness must be the site.
Light polarized parallel to the optical axis of a calcite crystal travels through the crystal normally (takes the ordinary path). Light polarized at right angles to this axis takes a deviant route (the extraordinary path).
Quantum theory works like a charm. Since its discovery in 1925 it has passed every test human ingenuity can devise, down to the last decimal point. However, like a magician who has inherited a wonderful magic wand that works every time without his knowing why, the physicist is at a loss to explain quantum theory’s infallible success.
Different people looking at the same theory come up with profoundly different models of reality, all of them outlandish compared to the ordinary experience which constitutes both daily life and the quantum facts.
The Copenhagenists believe that when an electron is not being measured, it has no definite dynamic attributes.
A pragmatist is concerned with results, not reality. The pragmatist refuses on principle to speculate about deep reality, such a concept being meaningless from his point of view. Pragmatism is an intellectually safe but ultimately sterile philosophy.
As an example of a Renninger-style measurement, consider a quantum system that possesses just two possibilities. The photon must take either path A or path B. We place a detector in path A and it does not click. The absence of a click in path A tells us that the photon must have taken path B. We have measured the position of a photon without explicitly interacting with it.
Record on tape a few minutes of traffic noise. If we analyzed this noise into tuba waveforms we could say that in a certain sense traffic noise is a chorus of tubas. But we could equally well say that it’s a chorus of pianos or saxophones. However, we know that real traffic noise has no intrinsic tuba, piano, or saxophone qualities.
The quantum world is objective but objectless.
The Copenhagen interpretation was bitterly challenged at first, but became during the thirties the orthodox interpretation of quantum theory, nominally accepted by almost all textbooks and practical workers in the field.
One of the drawbacks of the Copenhagen view is that it assigns a privileged role to measuring devices, describing them in terms of definite actualities, while every other entity is represented by superpositions of possibilities.
No elementary phenomenon is a real phenomenon until it is an observed phenomenon.
Wheeler’s delayed-choice experiment seems to show that the past is not fixed but alters according to present decisions.
Quantum theory itself does not say what is or is not a measurement but tells us that if we can find out how to make a measurement, it will predict the result.
A few physicists believe that record-making machines are not enough: only a conscious observation counts as a measurement (observer-creation of the second kind). Until conscious observers came upon the scene, the universe existed in an indefinite state, unable to decide even what kinds of attributes it possessed let alone their particular values.
Bishop Berkeley taught that matter possessed reality only insofar as it was perceived by some mind. No believer in observer-created reality, even the most extreme, goes as far as Berkeley. Every physicist upholds the absolute existence of matter—electrons, photons and the like—as well as certain of matter’s static attributes. However, observer-created reality physicists do believe that dynamic attributes—position and momentum, for instance—do not exist until they are actually observed.
Quantum waves do not make their home in ordinary three-dimensional space but in a place called configuration space. Configuration space consists of three dimensions for each quantum particle. The main reason that physicists consider the wave function to be fictitious is that it moves around in a space with many more dimensions than our own.
Everett’s quantum theory (the many worlds interpretation) without collapse describes the world as a continually proliferating jungle of conflicting possibilities, each isolated inside its own universe.
In the Everett picture everything that can happen does happen. If life on Earth is possible at all, then it is inevitable—in some corner of super reality.
All of a classical object’s attributes can be measured simultaneously: a classical object is completely open to view. A quantum entity is different: only a certain set of compatible attributes can be simultaneously measured.
Neorealists claim that the familiar objects that make up the everyday world are themselves made of ordinary objects; they believe, in short, that atoms are “things.” This straightforward view of the world’s real nature has been generally dismissed by establishment physicists as misguided and hopelessly naive.
Einstein once remarked, “Nature is clever, but she is not malicious.”
In his quantum bible Die Grundlagen, the most influential book on quantum theory ever written, von Neumann concludes that, from a strictly logical point of view, only the presence of consciousness can solve the measurement problem.
What’s special in von Neumann’s model is not the measuring device but the measurement act, where many waves suddenly shrink into one. Von Neumann showed that this special act—the wave function collapse or “quantum jump”—could be located anywhere without changing the final results, but it could not be eliminated.
In Berkeley’s philosophy—dubbed “idealism” because it emphasizes the primacy of ideas over things—nothing exists unless it is either a mind itself, or is perceived by a mind. “To be is to be perceived,” was the Irish bishop’s motto concerning matter: “All those bodies which compose the mighty frame of the world have no subsistence without a mind.”
Human beings are stuck in a Midas-like predicament: we can’t directly experience the true texture of reality because everything we touch turns to matter.
For thirty years physicists and philosophers beat their heads against the EPR paradox without either refuting EPR’s logic or shedding further light on EPR’s alleged “elements of reality.” In 1964 the long-standing EPR stalemate was broken by the efforts of theorist John Bell.
Bell’s theorem is a mathematical proof, not a conjecture or supposition. He does not merely permit or suggest that reality is non-local; he actually proves it.
Bell’s theorem is one of the clearest windows that physicists possess into the nature of deep reality.
The essence of a local interaction is direct contact—as basic as a punch in the nose. Body A affects body B locally when it either touches B or touches something else that touches B.
The essence of non-locality is unmediated action-at-a-distance. A non-local interaction jumps from body A to body B without touching anything in between. Voodoo injury is an example of a non-local interaction. When a voodoo practitioner sticks a pin in her doll, the distant target is (supposedly) instantly wounded, although nothing actually travels from doll to victim.
No one has so vehemently expressed physicists’ distaste for non-local interactions as Sir Isaac Newton: “That one body may act upon another at a distance though a vacuum without the mediation of anything else...is to me so great an absurdity, that I believe no man, who has in philosophical matters a competent faculty for thinking, can ever fall into.”
A non-local interaction links up one location with another without crossing space, without decay, and without delay. A non-local interaction is, in short, unmediated, unmitigated, and immediate.
Bell maintains that the world is filled with innumerable non-local influences. Furthermore these unmediated connections are present not only in rare and exotic circumstances, but underlie all the events of everyday life. Non-local connections are ubiquitous because reality itself is non-local.
The simplicity of Bell’s proof opens it to everyone, not just physicists and mathematicians.
Bell’s proof is based on the same EPR experiment used by Einstein, Podolsky, and Rosen to demonstrate the existence of hidden “elements of reality.”
As in the case of the EPR paradox, it’s important to realize what Bell did not do. He did not discover an experimental situation in which non-local interactions are directly observed. Instead he invented a simple argument based on experimental results that indirectly demonstrates the necessary existence of non-local connections.
Since it challenges one of physicists’ most cherished beliefs—that the world is fundamentally local—one might have expected Bell’s proof to explode like a bombshell in the corridors of science. Instead, Bell’s proof, published in an obscure little journal, was largely ignored even by those physicists who managed to find out about it.
Since it proposes no new experiments and derives no new phenomena-relevant mathematics, but merely puts certain constraints on an invisible reality, Bell’s proof lies outside the fashionable formula for success in science and is generally dismissed by scientists as “mere philosophy.”
Physicists’ cool reception of Bell’s proof is reminiscent of David Hume’s famous prescription for separating truth from nonsense: “Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion.”
A universe that displays local phenomena built upon a non-local reality is the only sort of world consistent with known facts and Bell’s proof.
For anyone interested in reality, Bell’s theorem is a remarkable intellectual achievement. Starting with fact plus a bit of arithmetic, Bell goes beyond facts to describe the contours of reality itself. Although no one has ever seen or suspected a single non-local phenomenon, Bell proves conclusively that the world behind phenomena must be non-local.
The world’s non-local underpinning is almost completely concealed—non-locality would have been discovered long ago if it were more evident; it leaves its mark only indirectly through the impossibly strong correlations of certain obscure quantum systems.
It’s easy to show (via Bell’s argument) that a local observer-created reality contradicts the quantum facts just as surely as does Bell’s original local (but otherwise unspecified) reality.
The arguments against Bell’s theorem (and their counterarguments) have become so recondite that a meeting of physicists on this topic sounds much like a congress of medieval theologians.
Even quantum logicians use Boolean logic when it comes to talking about quantum logic. In other words, the metalogic of quantum logic is Boolean.
Since Bell’s proof is based on experimental facts, it is independent of whether quantum theory is correct or not. Should quantum theory someday fail in its predictions or simply be replaced by an entirely different way of predicting the same quantum facts, Bell’s theory would still be valid. Bell’s theorem is derived from the facts themselves, not from any theoretical representation of these facts.
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